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Dag Linhjell

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Dag Linhjell

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Dag Linhjell
Telefon: 930 04 739
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Avdeling: Elkraftteknologi
Kontorsted: Trondheim

Publikasjoner og ansvarsområder

Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1920434/

Paper insulation on transformer windings may contain moisture, from aging or moisture ingress through breathers. A sudden overload will cause the insulation to heat much faster than the oil, and the moisture forced out of the insulation may not dissolve in the much colder oil, with bubbling as a...

År 2021
Type Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1816551/

The effect of pressure on positive and negative streamer propagation in a mineral transformer oil is studied in an 80 mm point-plane gap under step voltage. Increased pressure causes reduced stopping length for non-breakdown streamers, higher breakdown voltage, reduced background current, reduced...

Forfattere Dag Linhjell Lars Lundgaard M. Unge Olof Hjortstam
År 2020
Type Vitenskapelig artikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1807150/

This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under negative polarity stress. Stopping length for non-breakdown streamers, breakdown voltages and velocities for various pre-breakdown streamer modes have been studied for a selection of model liquids...

Forfattere Lars Lundgaard Dag Linhjell Øystein Hestad Michael Unge Olof Hjortstam
År 2020
Type Vitenskapelig artikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1807148/

This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under positive polarity stress. It is of interest to improve knowledge on how functional properties of dielectric liquids vary, as new brands arrive in the market, and existing standards are unsuited for...

Forfattere Dag Linhjell Lars Lundgaard Michael Unge Olof Hjortstam
År 2020
Type Vitenskapelig artikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1717940/

The propagation of positive streamers in a naphtenic transformer oil in an 80 mm point-plane gap has been investigated under an impulse voltage being close to a step voltage and under pressures ranging from 0.1 to 1.7 MPa. As has previously been found in short gap experiments of 1 – 7 mm in various...

Forfattere Dag Linhjell Lars Lundgaard Mikael Unge
År 2019
Type Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1526026/

Third mode streamers have been studied in the mineral oil Nytro 10 XN, gas-to-liquid oil Diala S4 ZX-1 and the high viscosity white oil Primol 352, in an 80 mm point-plane gap under step impulse voltage. Third mode streamer velocities were in the range 4–60 km/s. The "acceleration" of the average...

Forfattere Dag Linhjell Lars Lundgaard Mikael Unge
År 2017
Type Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1526028/

A sensitive differential charge measurement technique was used to measure the conduction current from a sharp needle in a needle plane geometry in n-pentane. The current was measured at voltages up to the threshold for streamer inception in n-pentane with a positive needle polarity. The measured...

Forfattere Øystein Hestad Dag Linhjell Lars Lundgaard Jarl Ø. Samseth Mikael Unge
År 2017
Type Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1526050/

For transformers in service, aging markers from cellulose in oil such as furans, water, methanol and acids are measured for diagnostic purposes. The content of these indicators, measured in oil, may therefore vary with load, temperature, solid and liquid insulation aging, as well as marker stability...

Forfattere Knut Brede Liland Dag Linhjell Cedric Lesaint Marit-Helen Glomm Ese Lars Lundgaard Pascal Mavrommatis Nenad Miroljub Stjepanovic
År 2017
Type Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1385663/

For introducing power converters at ambient pressure at large sea depths, dielectric liquids are proposed as insulation for power electronic converters. This paper presents statistical analysis of short time tests of partial discharge and breakdown voltage on the trench between metallized edges of...

Forfattere Abdelghaffar Amoka Abdelmalik Malin Drevdal Borge Arne Nysveen Lars Lundgaard Dag Linhjell
År 2016
Type Vitenskapelig artikkel
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/1060702/

This report addresses state of the art in the field of transformer ageing and diagnostics, with emphasis on advising end-users on transformer asset management and on transformer specification. The basis is results from two projects on laboratory studies on ageing of mineral oil impregnated cellulose...

Forfattere Lars Lundgaard Knut Brede Liland Dag Linhjell Dejan Susa Marit-Helen Glomm Ese Cecilie Mørk Selsbak M Kes Cedric Lesaint
År 2015
Type Rapport